[The relationship between psychiatry and neurology]. / Das Verhältnis von Psychiatrie und Neurologie.

Neurology and psychiatry deal with diseases of the (central) nervous system. Historically neurological disorders are related to a proven organic basis, whereas psychiatric disorders are mainly defined by the phenomenology and course of the symptoms. Neuroscientific research methods such as molecular genetics, neurochemistry, neurophysiology, neuropathology, functional (SPECT, PET, fMRI) or structural (MRI) imaging have dramatically increased our knowledge of psychiatric and neurological disorders in the last 20 years. Accordingly diagnostic and therapeutic procedures and the long-term prognosis of numerous diseases in both disciplines have substantially improved (i.e. pharmacotherapy, psychotherapy, functional neurosurgery). For major brain disorders - such as dementia of the Alzheimer type - close collaboration between both disciplines is developing in diagnosis, therapy and care. Due to common neurobiological research topics, educational programs, medical training and the challenges of assuring appropriate care to patients with brain disorders, further cooperation between neurology and psychiatry is expected and necessary.

Neural correlates of formal thought disorder in schizophrenia: preliminary findings from a functional magnetic resonance imaging study.

BACKGROUND: Formal thought disorder (FTD) is a core symptom of schizophrenia, but its pathophysiology is little understood. We examined the neural correlates of FTD using functional magnetic resonance imaging. METHODS: Blood oxygenation level-dependent contrast was measured using functional magnetic resonance imaging while 6 patients with schizophrenia and 6 control subjects spoke about 7 Rorschach inkblots for 3 minutes each. In patients, varying degrees of thought-disordered speech were elicited during each "run." In a within-subject design, the severity of positive FTD was correlated with the level of blood oxygenation level-dependent contrast in the 2 runs that showed the highest variance of FTD in each patient. RESULTS: The severity of positive FTD in patients was negatively correlated (P<.001) with signal changes in the left superior and middle temporal gyri. Positive correlations were evident in the cerebellar vermis, the right caudate body, and the precentral gyrus. CONCLUSIONS: The severity of positive FTD was inversely correlated with the level of activity in the Wernicke area, a region implicated in the production of coherent speech. Reduced activity in this area might contribute to the articulation of incoherent speech. Because of the small sample size, these findings should be considered preliminary.

Engagement of right temporal cortex during processing of linguistic context.

Language processing involves the interplay of areas in both cerebral hemispheres. Whereas the left temporal lobe is necessary for most language tasks, the right hemisphere seems to be additionally activated during processing of paragraphs and metaphors. We studied the neural correlates of word generation and selection in a sentence context, using functional magnetic resonance imaging (fMRI). Cerebral activation was measured while seven healthy, right handed volunteers read and completed sentence stems, with relatively low Cloze frequency, out loud. During a GENERATION condition, subjects were required to generate a word which completed a sentence stem appropriately. During a DECISION condition, subjects selected and articulated one of two presented terminal words. A READING condition in which subjects read an appropriate completion aloud, served as baseline. When GENERATION was compared to READING or DECISION, the left middle frontal, anterior cingulate, precuneus and right lateral temporal cortex were activated. During DECISION relative to READING, the left inferior frontal and middle/superior temporal cortex bilaterally were activated. The prominent engagement of the right lateral temporal cortex during the GENERATION conditions may reflect the processing of linguistic context, and particularly the activation of multiple meanings in the course of producing an appropriate completion.

Recognizing one's own face.

We report two studies of facial self-perception using individually tailored, standardized facial photographs of a group of volunteers and their partners. A computerized morphing procedure was used to merge each target face with an unknown control face. In the first set of experiments, a discrimination task revealed a delayed response time for the more extensively morphed self-face stimuli. In a second set of experiments, functional magnetic resonance imaging (fMRI) was used to measure brain activation while subjects viewed morphed versions of either their own or their partner's face, alternating in blocks with presentation of an unknown face. When subjects viewed themselves (minus activation for viewing an unknown face), increased blood oxygenation was detected in right limbic (hippocampal formation, insula, anterior cingulate), left prefrontal cortex and superior temporal cortex. In the partner (versus unknown) experiment, only the right insula was activated. We suggest that a neural network involving the right hemisphere in conjunction with left-sided associative and executive regions underlies the process of visual self-recognition. Together, this combination produces the unique experience of self-awareness.

Differential activation of temporal cortex during sentence completion in schizophrenic patients with and without formal thought disorder.

The neural correlates of processing linguistic context in schizophrenic patients with formal thought disorder (FTD) were examined. Six right-handed male patients with prominent 'positive' FTD were compared with six schizophrenic patients without FTD and seven volunteers, matched for cognitive and demographic variables. Functional magnetic resonance imaging (IMRI) was used to measure cerebral activation while subjects read and completed sentence stems out loud. During a GENERATION condition, subjects were required to generate a word which completed the sentence stem appropriately. During a DECISION condition, subjects selected and articulated one of two presented terminal words. A READING condition served as baseline. The three conditions were compared with each other. Regions activated were identified in each group, and between-group differences were detected using an ANCOVA. When GENERATION was compared with READING, FTD patients showed less activation in the right superior temporal gyrus than patients without FTD or controls, but greater activation in the left inferior frontal, inferior temporal and fusiform gyri. FTD patients also showed an attenuated right temporal response when GENERATION was compared with DECISION. This differential engagement of the right temporal cortex was independent of differences in the speed or accuracy of responses, whereas the left fronto-temporal differences in activation were not evident after covarying for task errors. The attenuated engagement of right temporal cortex, which is implicated in language comprehension at the discourse level, is consistent with neuropsychological evidence linking thought disorder with deficits in processing linguistic context.

Activation of right fronto-temporal cortex characterizes the 'living' category in semantic processing.

It is a vital ability for humans to distinguish between living and non-living objects. Whether the semantic features of these two classes of objects are represented in distinct brain areas, is unknown. In our study, words belonging to the categories 'living' and 'non-living' were presented visually to twelve right-handed volunteers, while brain activation was measured with event-related fMRI. Subjects had to judge whether the item belonged to one of these categories. Common areas of activation (P<0.05, corrected) during processing of both categories include the inferior occipital gyri bilaterally (BA 17/18), left inferior frontal gyrus (BA 44/45) and left inferior parietal lobe (BA 40). During processing of 'living' minus 'non-living' items, signal changes (P<0.05, corrected) were present in the the right inferior frontal (BA 47), middle temporal (BA 21) and fusiform gyrus (BA 19). Our results are in line with findings from patients with a deficit in semantic processing of living things, who specifically suffer from right hemispheric lesions.

Towards a functional neuroanatomy of self processing: effects of faces and words.

We studied the neural correlates of self vs. non-self judgements using functional magnetic resonance imaging (fMRI). Individually tailored faces and personality trait words were used as stimuli in three experiments (exp.). In the first two experiments, brain activation was measured while subjects viewed morphed versions of either their own (self face exp.) or their partner's face (partner's face exp.), alternating in blocks with presentation of an unknown face. In the self face exp. right limbic areas (hippocampal formation, insula, anterior cingulate), the right middle temporal lobe, left inferior parietal and left prefrontal regions showed signal changes. In the partner's face exp., only the right insula was activated. In the third exp., subjects made decisions about psychological trait adjectives previously categorized as describing their own attributes. Activation was present in the precuneus, the left parietal lobe, left insula/inferior frontal gyrus and the left anterior cingulate. A reaction time advantage was present when subjects responded to self-relevant words. The main area with signal changes during self-reference processing, regardless of the type of stimulus, was the left fusiform gyrus. The self-relevant stimuli engaged to a differential extent long term and working memory, semantic and emotional processes. We suggest that regions activated by these stimuli are engaged in self-processing.

Lexical retrieval during fluent speech production: an fMRI study.

We investigated the neural correlates of lexical retrieval during fluent speech production using fMRI. Blood oxygenation level dependent (BOLD) contrast was measured while subjects spoke about 7 Rorschach inkblots for 3 min each. Varying degrees of speech rate were elicited during each run. In a within-subject design, the number of words produced was correlated with the BOLD contrast in the two runs in each subject that showed the highest variance of speech output. The rate of articulation was positively correlated with activation in the left superior temporal (BA 22) and supramarginal (BA 39/ 40) gyri. The main negative correlations were in the fusiform gyri bilaterally (BA 19), the posterior cingulate (BA 30) and superior occipital gyrus (BA 19). Lexical retrieval during continuous language production engages areas in the left temporal and inferior parietal cortex. This pattern of activation differs from that evident during the generation of single words (verbal fluency), which is more associated with left prefrontal activation.

Differential activation in parahippocampal and prefrontal cortex during word and face encoding tasks.

Episodic encoding is the first step in the formation of a memory trace. The relation between type of stimulus material and regional brain activation is not fully understood. We measured brain activation using fMRI in 12 healthy subjects during two experiments, word and face encoding. A widespread network of common activations in both tasks was present in the bilateral frontal (BA44/45), occipital (BA17/18/19) and fusiform gyri (BA37) as well as the right hippocampal formation (BA30). A region-of-interest-analysis for the hippocampal formation and dorsolateral prefrontal cortex (DLPFC) was performed additionally. During face encoding the right dorsal and during word encoding the bilateral ventral hippocampal region was activated. In the prefrontal cortex a lateralization to the left side was present only for word encoding. During encoding, activation in the inferior frontal and hippocampal cortex is modulated by the type of stimulus material.

Faulty suppression of irrelevant material in patients with thought disorder linked to attenuated frontotemporal activation.

Formal thought disorder is a feature schizophrenia that manifests as disorganized, incoherent speech, and is associated with a poor clinical outcome. The neurocognitive basis of this symptom is unclear but it is thought to involve an impairment in semantic processing classically described as a loosening of meaningful associations. Using a paradigm derived from the n400 event-related, potential, we examined the extent to which regional activation during semantic processing is altered in schizophrenic patients with formal thought disorder. Ten healthy control and 18 schizophrenic participants (9 with and 9 without formal thought disorder) performed a semantic decision sentence task during an event-related functional magnetic resonance imaging experiment. We employed analysis of variance to estimate the main effects of semantic congruency and groups on activation and specific effects of formal thought disorder were addressed using post-hoc comparisons. We found that the frontotemporal network, normally engaged by a semantic decision task, was underactivated in schizophrenia, particularly in patients with FTD. This network is implicated in the inhibition of automatically primed stimuli and impairment of its function interferes with language processing and contributes to the production of incoherent speech.

Reversed lateralization of temporal activation during speech production in thought disordered patients with schizophrenia.

BACKGROUND: Formal thought disorder is a core symptom of schizophrenia. It is associated with a reversed lateralization of the superior temporal cortex volume, an area that is implicated in lexical retrieval. We investigated the neural correlates of word retrieval during continuous speech in patients with formal thought disorder using functional magnetic resonance imaging (fMRI). METHODS: Blood oxygenation level dependent (BOLD) contrast was measured with fMRI while six patients with schizophrenia and six healthy control subjects spoke about seven Rorschach inkblots for 3 min each. Subjects produced varying amounts of speech during each run. In a within subject design, the number of words produced was correlated with the BOLD contrast in the two runs in each participant who showed the highest variance of speech output. RESULTS: In control subjects, the amount of speech produced was mainly correlated with activation in the left superior temporal gyrus. In the patient group, the main correlations were in the right superior temporal gyrus. CONCLUSIONS: During the production of continuous speech, patients with formal thought disorder showed a reversed laterality of activation in the superior temporal cortex. This is consistent with findings of perturbed hemispheric interaction in schizophrenia, particularly in patients with formal thought disorder.